The present invention relates to a new and improved construction of a safety apparatus for a spinning projectile fuze.
Generally speaking, the safety apparatus of the present development is of the type comprising a rotor which, upon firing of the projectile, can be moved out of a safety position into an armed or live position and the axis of which is mounted externally of the spin axis of the projectile. A retarding or restraining mechanism is also provided which releases the rotor, following firing of the projectile and after a certain time-delay in order to allow it to rotate into the armed or live position. A first safety element is responsive to the firing acceleration and to the spin and serves to release the rotor in order to enable it to rotate into the live position, whereas a second safety element, responsive to the spin of the projectile, serves to release the rotor to enable it to rotate into the armed or live position.
Different requirements are placed upon a safety apparatus for a fuze and as to the more important ones they can be enumerated as follows:
The interruption of a firing or ignition chain in the fuze must be accomplished such that the first element of the ignition chain, until releasing the safety, must be separated by at least one blocking device or safety apparatus from the transmission charge and the reinforcement charge. The safety apparatus must be directly mechanically lockable by means of at least two independently operating safety elements. Each safety element must be actuated by at least one environmental force which does not act upon the other safety element. If the ignition chain is not positively interrupted because the safety or blocking apparatus is missing, then the fuze must be designed in a manner such that it is impossible to assemble the fuze without the blocking or locking element.
There are known to the art quite a number of safety apparatuses of this type. Attention is specifically directed to Swiss Pat. No. 531,159 wherein there is provided a rotor which is operatively connected with a retarding mechanism. However, this state-of-the-art arrangement is afflicted with the drawback that the rotor already begins to rotate at such time as the restraining mechanism begins to operate. This prior art apparatus furthermore possesses a safety element which is responsive to the firing acceleration. This known safety element, however, possesses the drawback that it exclusively responds to firing acceleration and not additionally to the projectile spin.
Furthermore, there is known from German Pat. No. 2,247,709 a safety apparatus of this type which likewise possesses a rotor which is operatively connected with a restraining mechanism. The rotor first can begin to rotate when the action of the restraining mechanism has expired. What is disadvantageous with this known arrangement is, however, that the restraining or retarding mechanism possesses a swinging or oscillatory armature, the pivot axis of which is located externally of the spin axis of the projectile. Consequently, there is not ensured or reliable functioning of the restraining mechanism.